Laboratory studies indicate that relatively high concentrations (1.000 - 10.000 ppm) of humic acids can increase the leaching of chromium and copper from CCA-C treated wood, and that copper is most affected. They also show that leaching with natural water samples can result in higher leaching of all components than leaching with distilled water. Evaluation of CCA component retentions and mass balances in the surface 5mm of poles in service shows that copper and arsenic are significantly leached from the portions of the poles in contact with water in wet sites, whereas chromium leaching does not appear to be affected by location in the pole or by site. Arsenic losses also appear to increase more with age of the pole compared to the other components. Regression analysis shows that the concentration of CCA components in water near poles in wet sites increases with higher natural humic acid concentrations and with decreasing water pH. However, the analysis of CCA component levels and mass balances in the surface wood in contact with water in service are not related in the same way, and in fact are higher in sites with higher humic acid content and lower pH.

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